How to Beat Isshin, the Sword Saint

Location: Ashina Reservoir (Final Boss for Immortal Severance, Purification, Return endings)
Deathblows: 4
Weaknesses: Mikiri Counter, Lightning Reversal, Shinobi Firecrackers
Strategy: This is the ultimate test. Phase 1 (Genichiro, Way of Tomoe): Similar to your previous fight with him. Deflect, Mikiri, and Lightning Reversal. Phase 2 (Isshin, Katana & Spear): He uses a katana and a long spear. Deflect his spear attacks and Mikiri Counter his thrusts. Stay aggressive. Phase 3 (Isshin, Katana, Spear & Gun): He adds a gun and lightning attacks. Utilize Lightning Reversal. Phase 4 (Isshin, even more aggressive): He becomes incredibly fast and powerful. Maintain perfect deflections, Mikiri Counters, and Lightning Reversals. Shinobi Firecrackers can create small openings. This fight demands mastery of all Sekiro's combat mechanics. Reward: Memory: Isshin, the Sword Saint, Dragon Flash.